Alopecia (Baldness)

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Causes

Folliculitis decalvans, also known as alopecia folliculitis or acne decalvans, is an inflammatory reaction in hair follicles on the scalp that causes redness (erythema) and pus-filled blisters (pustules). It leads to scarring and permanent hair loss.

Traction alopecia occurs as a result of improper hair care and prolonged use of certain hair-styling techniques. Cosmetic treatments (e.g., dyes, tints, bleaches, permanents) are generally safe; however, if treatments are done incorrectly, or if the chemicals are used for too long, the hair becomes brittle and breaks easily.

Hairstyles that pull the hair tightly, and excessive shampooing or brushing can also cause hair loss. Braiding, permanents, excessive heat, and hair straightening cause hair shaft weakness. Hair styling techniques such as hair weaving, corn rowing, and the use of hot combs to straighten hair can cause permanent hair thinning and scarring.

Stress alopecia, a type of telogen effluvium, is temporary, reversible, diffuse hair loss on the scalp that results from severe emotional or physiological stress. Normally, about 90% of scalp hair follicles are in the growing anagen phase, and about 10% to 15% are in the resting catagen and telogen phases. Stress causes anagen hairs to convert prematurely into telogen hairs, which means that more than the normal number of hairs are in the telogen phase and ready to shed.

Exposure to various drugs can induce a temporary alopecia. Patients concerned about hair loss or thinning should notify their doctor or other health care provider about medications they are taking. A number of prescription drugs, including certain medicines for arthritis, depression, heart problems, and high blood pressure can cause hair loss. Spontaneous regrowth usually occurs after the drug is stopped. The hair loss effect of some drugs can be prevented by cooling the scalp with a tight-fitting ice bag for 20 minutes or so while receiving the drug treatment.

Toxic alopecia (anagen effluvium) occurs when hair growth is disrupted during the anagen phase. The newly synthesized hair shafts weaken, and the hair breaks. Hair loss is usually quick and involves all the hairs in the anagen phase. Chemotherapy, radiotherapy to the scalp, and overdoses of vitamin A can cause toxic alopecia. Chemotherapy can cause 90% hair loss. The hair regrows when treatment ends.

During hormonal changes after childbirth, when the hormones revert to normal levels, all of the hair that has not been cycling suddenly enters the resting, telogen phase. For several months following childbirth, women may notice that more hair than usual falls out when they comb or brush.

Women who are susceptible to androgenetic alopecia and take birth control pills may experience hair loss. Switching birth control pills sometimes helps. Women who stop using oral contraceptives may notice their hair thinning 2 or 3 months later. The hair starts to grow normally after about 6 months.

Illness can cause hair loss. Often, for the first couple of months after serious illness, the hair enters a resting phase and starts to shed. Hair loss also may follow major surgery. Patients with a chronic illness may lose hair continually. Hypothyroidism can lead to diffuse hair loss on the scalp and dry, brittle hair. Syphilis can sometimes cause spotty hair loss.

Ringworm (tinea capitas), a contagious childhood disease, can lead to the development of inflammatory, boggy masses full of broken hairs and ooze (called kerions). Kerions usually heal but can leave permanent bald patches.

Seborrheic dermatitis, or eczema, is often associated with diffuse hair thinning and greasy, yellow scales on the scalp. Treatment usually involves tar shampoo and topical steroids.

Trichotillomania, compulsive hair pulling, can eventually lead to alopecia. As many as 6 to 8 million Americans suffer from this condition.

If a person does not eat enough protein, the body tries to make up for the deficiency by stimulating an abnormally large number of hairs to enter the resting phase of the hair growth cycle. A couple months later, those hairs shed.

Iron deficiency also can produce hair loss. For example, a woman who bleeds heavily during her periods may develop iron deficiency and associated hair loss.

Patient Resources

Some of the information in this document was adapted from the National Alopecia Areata Foundation, an organization that provides information on alopecia areata, funding for scientific research, and emotional support for patients and their families.

Alopecia (Baldness), Causes reprinted with permission from dermatologychannel.net
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